10 Java One-Liners That Will Make You Look Like a Pro

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 🧾 Introduction

Writing good Java code is not just about making things work.
 It’s about writing clean, short, and smart code that looks professional.

Sometimes, you don’t need 5 lines when one smart line can do the job.

In this guide, you’ll learn 10 powerful Java one-liners that can:

✅ Make your code cleaner
✅ Save time during coding
✅ Impress interviewers and teammates

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✅ 1. Swap Two Variables Without Temp Variable (Java 7+)

a = a + b - (b = a);

Explanation:

• Smart arithmetic trick to swap two integers without using a third variable.
• But use carefully to avoid confusion — prefer readability when needed.

✅ Works great for quick algorithm tricks.

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✅ 2. Initialize a List in One Line (Java 9+)

List<String> fruits = List.of("Apple", "Banana", "Cherry");

Explanation:

• List.of() quickly creates an immutable list without needing new ArrayList<>() and manual adds.

✅ Cleaner and faster setup for small lists.

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✅ 3. Find Max of Two Numbers

int max = Math.max(a, b);

Explanation:

• Built-in method — no need for manual if-else to find maximum.

✅ Clean and fast.

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✅ 4. Read All Lines from a File

List<String> lines = Files.readAllLines(Path.of("file.txt"));

Explanation:

• Java NIO makes reading a whole text file into a list super easy.

✅ No more messy BufferedReader loops if you just need all lines.

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✅ 5. Convert List to Comma-Separated String

String result = String.join(", ", fruits);

Explanation:

• Quickly joins list elements into a single string with commas.

✅ Very useful for logs, APIs, CSV formats.

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✅ 6. Remove Null Values from a List

list.removeIf(Objects::isNull);

Explanation:

• removeIf + method reference removes all null entries in one line.

✅ No need for manual for loops and checks.

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✅ 7. Get a Random Element from a List

String randomFruit = fruits.get(new Random().nextInt(fruits.size()));

Explanation:

• Pick a random item by generating a random valid index.

✅ Quick random selections for games, tests, etc.

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✅ 8. Count Items Matching a Condition

long count = list.stream().filter(x -> x > 10).count();

Explanation:

• Stream + filter + count in one clean line.

✅ Great for statistics, data filtering, and analytics.

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✅ 9. Sort a List in Descending Order

list.sort(Comparator.reverseOrder());

Explanation:

• Sorts the list in descending order with one simple call.

✅ No need to write custom comparators manually.

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✅ 10. Check If a String is a Palindrome

boolean isPalindrome = str.equals(new StringBuilder(str).reverse().toString());

Explanation:

• Reverse the string using StringBuilder and compare with the original.

✅ Perfect one-liner for quick coding rounds and interviews.

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📌 Quick Recap: 10 Java One-Liners You Should Know

✅ Final Thoughts

You don’t need to write long, complicated code to be impressive.
Sometimes, one smart line is all it takes to show you know what you’re doing.

✅ Master these one-liners.
✅ Use them wisely — keeping code clean, not confusing.
✅ And you’ll look like a pro in interviews, team discussions, and real-world projects.

Good developers write code.
Great developers write smart, clean, efficient code.